Method of making water-soluble capsules for cosmetic purposes



Patented Aug- 22, 1939 PATENT OF-FICE METHOD OF MAKING WATER-SOLUBLE CAPSULES FOR oosml'rlcrunrosss Karl Wilhelm Schmidt, Nuremberg Germany No Drawing. Application Mal-tits, 1938, Serial No. 194,641. In Germany November 26, 1937 1 Claim.

It is known to pack bathing-salts and cosmetic preparations in water-soluble capsules e. g; such made of urea, and to bring the filled capsule into the washing or bathing water,

thus into the water.

From this, the following facts. have turned out: The cosmetic products. contain perfume, ethereal oils and easily volatile substances, If such substances are filled into a capsule of the through the wall oi the capsule, the surface of the capsule becomes insignificant, and the easily volatile substancesvanish after a short time. 5 I have now found out, that thisinconvenienoe can be partly done away with, if when pressingjhe capsules e. g. of urea, a pressure of at least 1000 kg/cm is used, in order to fasten the walls of the capsule at a great exto tent. Capsules which are made in this way i show a considerable density andsatisfy the normal exigencies relating to their capability of being stored. For higher exigencies even this measure is not suflicient. g I have, however, succeeded in making an absolute dense capsule, .byapplying to its inner side a prepared layer. Such a layer must satisfy difierent exigencies: The layer must be a coherent film, it must ,vanish when the, capsule dissolves in the bathing water, and it must not injure the smell nor react chemically with the contents of the capsule.

For this purpose of preparation, sodium stearate has proved to be well adapted, which, when brought upon the surface of the capsule in alcoholic solution and after having evaporated, gives a close layer. Instead of this compound, also sodium palmitate or sodium oleate may be used, Sodium resinate is usable, too. Furtherlo more, there may be taken hexene 1. 6 -diol and urethane, which are favourable because of their low meltingpoint and of their great watersolubility.

All these substances are water-soluble. There 5 .may, however, be taken such substances which are not water-solublebut will melt in water of a. slightly higher temperature, especially in the normal temperature of bathing water. I have found out, thata mixtureiof higher solidparaf- 50 fines with a meltingpoint of about 40 C., as

IIS where the capsule dissolves, its contents getting known kind, they diffuse comparatively quickly By this, a refreshing effect upon the body is I the same timethe bath is perfumed.

. kg/cmKto' render the particles of urea forming chemical series which have a lower melting point," the so-called parafline oils. ,Rlrther'more are apt for-the given purpose: glycerides of palmitic acid, of stearic acid, and of 'oleic acid; The melt- 'ing point of such a mixtureis loweredaccording .as'the-percentage of the glyceride of oleic acidv is increased. 5 Substances of this kind can beplaced upon 'the surface of the wall of the capsule in a melted state. By means of such an isolating layer, still other effects can be obtained. If hydro-aromatic compounds of the terpeneseries are used, theisolating layeritself can be made the aromatic substance or its bearer. So e. g. menthol has the. property of melting at the temperature of the bathing water and of sticking to the skin.

obtained, similar to the one obtained by 'massage oils. Also terpentine oil belongs to the substances of this class, its melting point be- I ing at 0.; it has the smell of elder, so that at l 20 Instead of bringing the isolating means as a] special layer upon the surface of the; capsule to be pressed, this means can also be added to the pressing mass. For this, besidethe saidsubstances, also higher melting substances are suit-a. able, because the process of pressing brings about. a warming of the mass and may beexecuted under the supply of heat. E. g. a parafline with aImelting point of 40-.60 .C.. can beadded to the pressing mass in a quantity of 14%. By this small admixture, the solubility of the capsule is not diminished. In the same way, stearine may be applied. The admixtures are dissolved in a suitable solvente. g. ether, and mixed to the pressing mass. After the ether is evaporated, the mass is ready to be worked up. Capsules made of such a mass show no more the former drawbacks. Besides, there arises an advantage, as the pressure y be lower than would be necessary without the admixture. The scope of the employable substances is not limited by the above-named examples. 3

I- claim:

A method ofmaking water .soluble jcapsules ,for cosmetic purposes, in which the content of the capsules-is of easily volatile products, which consists in forming urea to theshape of a cap sule, 'and'subjectingthe urea when so formed to capsule shape to a pressure of at least 1000 sule. I 

